As disclosed in my U.S. Pat. Nos. 3,507,412; Apr. 21, 1970 and 3,700,519; Oct. 24, 1972, the use of an air impervious conveyor tube which becomes an integrated part of the completed pipe assembly of resin and fiber in a continuous method of making the pipe assembly is known. In continuous methods of making fiber reinforced plastic pipe it has been the practice to use mandrels. Some provision must be made to prevent the conveyor tube from sticking to the mandrel. As disclosed in the aforementioned patents, a belt system has been used wherein the belts are coated with a mold release material. Also, and particularly where the conveyor tube will be made to provide a resin-rich surface on the interior of the pipe, or will be saturated with a resin composition, a cellophane casing has been used for contact with the mandrel. The cellophane acts as a release material, and must be subsequently stripped from within the finished pipe assembly.
A primary object of the present invention is to provide a method of continuously making fiber reinforced plastic pipe of the type having a resin-saturated conveyor tube which becomes an integrated part of the finished pipe assembly wherein it is unnecessary to resort to a stripping step, or to remove release material from within the finished product. Further, the conveyor tube preferably is made so that it has a resin-rich inner surface or liner. Nevertheless, it is unnecessary to use a belt assembly or a like mechanism in order to enable the manufacture of the product.
As will hereinafter appear, the method of the invention is simple. The equipment used to fabricate the pipe is of simple construction, and the steps involved to produce the product are minimal in number, particularly in that it is not necessary to resort to a final stripping step though the finished product includes a resin-rich liner.